1. Ensure the Backup icon is in your system bar at the top of the screen:
If this does not exist go to the Application Folder and Relaunch Backup Client and make sure the icon is displayed in the system bar.
2. On the inactive system ensure that Backup Client exists in your application folder.
If does not please reinstall the backup client by following the steps in the FAQ: Installing Continuous Client for Mac
If there has been no new data you can check the folders you have selected for backup locally and confirm that the last modified date on these folders to see if there should have been new data backed up or not or if there just has been no new data.
If you do have additional concern or still not sure if they backups are running as intended please contact support for additional assistance.